Pregnancy and serum-creatine-kinase levels in potential carriers of Duchenne X-linked muscular dystrophy

Normalization of creatine kinase level during pregnancy in idiopathic hyperCKemia

A 34-year-old previously healthy woman with no remarkable family history developed asymptomatic hyperCKemia at age 26. Over the next 6 years, hyperCKemia persisted (502-2562 IU/l; normal range<180). A muscle biopsy showed minimal nonspecific myopathy. Genetic analysis of blood and muscle samples showed no abnormality in the dystrophin gene. At age 33, she became pregnant for the first time and serum creatine kinase (CK) was normal at 170 IU/l in the third trimester. After delivery, hyperCKemia reappeared (715-2620) while her baby tested normal for CK. This is the first report of idiopathic hyperCKemia associated normalization of serum CK level during pregnancy, which has been reported in carriers of Duchenne muscular dystrophy.

Pyruvate-kinase (PK) and creatine-kinase (CK) in normal pregnancy and its implication in genetic counseling of Duchenne muscular dystrophy (DMD)

The activities of pyruvate-kinase (PK) and creatine-kinase (CK) were measured in 50 normal pregnant women in both serum and amniotic fluid. Serum PK activity was found to be significantly higher in pregnant than in nonpregnant women, while serum CK did not differ significantly between the two population samples. In amniotic fluid, very little or no PK or CK activity was found. However, the mean PK activity in amniotic fluid obtained from women carrying male fetuses was significantly higher than in those carrying female fetuses. At the present time, it is concluded that if a woman at risk for having a son with Duchenne dystrophy is seeking genetic counseling when already pregnant her serum PK or CK should be compared with that of normal female pregnant controls. It is also suggested that determination of pyruvate-kinase in fetal blood might be used in addition to CK for prenatal diagnosis of Duchenne muscular dystrophy.

Variation of serum creatine kinase levels with age in normal females: implications for genetic counselling in Duchenne muscular dystrophy

We have examined the variation of creatine kinase (CK) levels with age in 206 unrelated normal females. The subjects included 75 adult women aged 15-50, 11 post-menopausal women aged 50-70 and 120 girls under 15 years of age, comprising 84 girls with idiopathic epilepsy (65 pre-menarchal and 19 post-menarchal), well controlled on various anticonvulsant combinations, and 36 normal schoolgirl volunteers (28 pre-menarchal and 8 post-menarchal). Comparison of mean and variance values showed no significant difference between the CK levels in normal and epileptic girls and the data were subsequently combined. Creatine kinase levels were significantly higher in the pre-menarchal girls than in the post-menarchal girls and normal adult women. Levels were high in the first few months of life, fell during infancy and early childhood, rose rapidly in later childhood and then fell abruptly around the time of menarche. The levels then fell slowly throughout adult life but rose again after age 40. This phasic variation with age may be related to hormonal status. The use of age-specific CK ranges may have a significant effect on the carrier detection rate in Duchenne dystrophy.

Effect of age on the detection rate in Duchenne muscular dystrophy

In order to estimate SCK (serum creatine kinase) variability with age in carriers of Duchenne dystrophy (DMD), repeated SCK determinations in 10 obligate and 19 possible carriers were performed over a period of several years. Although there was some variation in some individuals, the differences in SCK means and risks of heterozygosity were not statistically significant between the first and second determinations. The present investigation indicates that the relation between SCK and age in carriers of the Duchenne gene is still controversial.

Serum creatine kinase levels in pubertal, mature, pregnant, and postmenopausal women

In order to obtain control values for the diagnosis of carriers of Duchenne muscular dystrophy, creatine kinase (CK) estimations were performed in two laboratories on 148 healthy teenage girls (of whom 38 were premenarchal and 110 postmenarchal), 133 healthy mature women, 124 pregnant women, and 37 postmenopausal women. These levels were highest in the premenarchal teenagers, and became successively lower in the postmenarchal teenagers, the mature women, and the pregnant women, so that the mean level of the pregnant women was less than half that of the teenagers. The CK levels then rose again after the menopause. If the distribution of CK levels in adult non-pregnant women had been taken as controls for teenagers who were possible carriers for Duchenne muscular dystrophy, then one third of those teenagers classified as carriers would have been so classified incorrectly.